The included pictures show the clearance a 13x6 prop has when the GP Skybolt ARF is parallel to the ground as it would be when touching down in a 2point landing or as it would be after rotating on takeoff. Please note the stack of books that were used to "level" the airplane. I carefully selected each one in order to more accurately elevate the model and the level of this thread.

The steel right angle ruler was used to show that the prop was perpendicular. The measurement actually will err on the long side, since the ruler pressed into the carpet more than the tires of the airplane did.

As the pictures show, a 13" prop on the ARF Skybolt would have about 2 1/4" clearance. A 15" prop would have about 1 1/4" clearance. Those distances would be accurate off paved runways and would suggest how your prop would clear relative to the depth of the grass on your field.